Hatchway cover structure is indicated in the prior art such as a unitary structure presented by U.S. Pat. No. 4,658,555 and the U.S. Pat. No. 4,832,153. U.S. Pat. No. 5,220,757 indicates a hatchway cover wherein a plate is movable between a first position and a second position to permit closure of a hatchway opening, as the structure is slidably mounted for such movement. U.S. Pat. No. 5,274,966 indicates a cover for a stair opening utilizing an interfitting .[.polyurathan.]. .Iadd.polyurethane .Iaddend.type housing cover.